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|
=pod
=head1 NAME
B<funsky - convert between image and sky coordinates>
=head1 SYNOPSIS
funsky iname[ext] # RA,Dec (deg) or image pix from stdin
funsky iname[ext] [lname] # RA, Dec (deg) or image pix from list
funsky iname[ext] [col1] [col2] # named cols:units from stdin
funsky iname[ext] [lname] [col1] [col2] # named cols:units from list
=head1 OPTIONS
-d # always use integer tlmin conversion (as ds9 does)
-r # convert x,y to RA,Dec (default: convert RA,Dec to x,y)
-o # include offset from the nominal target position (in arcsec)
-v # display input values also (default: display output only)
-T # output display in rdb format (w/header,tab delimiters)
=head1 DESCRIPTION
Funsky converts input sky coordinates (RA, Dec) to image coordinates (or vice
versa) using the WCS information contained in the specified FITS file. Several
calling sequences are supported in order to make it easy to specify
coordinate positions in different ways.
The first required argument is always the input FITS file (or
extension) containing the WCS information in an extension header. Note
that the data from this file is not used. By default, the program
converts input RA and Dec values to X and Y using this WCS
information. If the WCS is associated with a FITS image, then the X,Y
values are image values. If the WCS is associated with a binary table,
then the X, Y values are physical values. To convert X,Y to RA and
Dec, use the B<-r> (reverse) switch.
If no other command arguments are supplied, then the input positions
are read from the standard input. Each line is assumed to contain a
single coordinate position consisting of an RA in degrees (or X in
pixels) followed by a Dec in degrees (or Y in pixels). The usual
delimiters are supported (spaces, commas, tabs). For example:
# read from stdin, default column names and units
[sh] funsky snr.ev
22.982695 58.606523 # input RA (hrs), Dec(deg)
510.00 510.00
22.982127 58.607634 # input
512.00 510.50
22.981700 58.614301 # input
513.50 513.50
^D # end of input
If a second argument is supplied, this argument is assumed to be
a file containing RA (X) and Dec (Y) positions. The file can either be
an ASCII table or a FITS binary table. The order of columns is
unimportant, if the table has a column header. In this case, the
names of the columns must be one of "RA", "DEC", or "X", "Y" for sky
to image and image to sky conversions, respectively. If the table has
no header, then once again, RA (X) is assumed to first, followed
by DEC (Y).
For example:
# read from file, default column names and units
[sh] cat hd.in
RA DEC
--------- ---------
22.982695 58.606523
22.982127 58.607634
22.981700 58.614301
[sh] funsky snr.ev hd.in
510.00 510.00
512.00 510.50
513.50 513.50
If three arguments are supplied, then the input positions again are
read from the standard input. Each line is assumed to contain a single
coordinate position consisting of an RA (or X in pixels) followed by a
Dec (or Y in pixels), with the usual delimiters supported. However,
the second and third arguments now specify the column names and/or
sky units using a colon-delimited syntax:
[colname]:[h|d|r]
If the colname is omitted, the names default to "RA", "DEC", "X", "Y",
"COL1", or "COL2" as above. If the units are omitted, the default is degrees
for both RA and Dec. When the -r switch is used (convert from image
to sky) the units are applied to the output instead of the input. The following
examples will serve to illustrate the options:
# read from stdin, specifying column names (def. units: degrees)
[sh] cat hd.in
MYRA MYDEC
--------- ---------
22.982695 58.606523
22.982127 58.607634
22.981700 58.614301
[sh] funsky snr.ev MYRA MYDEC < hd.in
510.00 510.00
512.00 510.50
513.50 513.50
# read from stdin, specifying column names and units
[sh] cat dd.in
MYRA MYDEC
--------- ---------
344.740432 58.606523
344.731900 58.607634
344.725500 58.614301
[sh] funsky snr.ev MYRA:d MYDEC:d < dd.in
510.00 510.00
512.00 510.50
513.50 513.50
# read stdin, convert image to sky, specifying output sky units
[sh] cat im.in
510.00 510.00
512.00 510.50
513.50 513.50
[sh] cat im.in | funsky -r snr.ev :d :d
344.740432 58.606523
344.731900 58.607634
344.725500 58.614301
Finally, four command arguments specify both and input file and column names
and/or units:
[sh] cat dd.in
MYRA MYDEC
--------- ---------
344.740432 58.606523
344.731900 58.607634
344.725500 58.614301
[sh] funsky snr.ev dd.in MYRA:d MYDEC:d
510.00 510.00
512.00 510.50
513.50 513.50
# read file, convert image to sky, specifying output sky units
[sh] cat im.in
510.00 510.00
512.00 510.50
513.50 513.50
[sh] funsky -r snr.ev im.in :d :d
344.740432 58.606523
344.731900 58.607634
344.725500 58.614301
By default, the output of funsky consists only of the converted coordinate
position(s), one per output line. This makes parsing in shell scripts easy.
Use the B<-v> (verbose) switch to specify that the input
coordinates should be pre-pended to each line. For example:
[sh] cat dd.in
MYRA MYDEC
--------- ---------
344.740432 58.606523
344.731900 58.607634
344.725500 58.614301
[sh] funsky snr.ev dd.in MYRA:d MYDEC:d
510.00 510.00
512.00 510.50
513.50 513.50
[sh] funsky -v snr.ev dd.in MYRA:d MYDEC:d
344.740432 58.606523 510.00 510.00
344.731900 58.607634 512.00 510.50
344.725500 58.614301 513.50 513.50
In addition, a full starbase table can be output using the B<-T>
(table) switch. This switch can be used with or without the -v
switch. If the -T and -v are both specified, then a descriptive header
parameters are output before the table (mainly to remind you of the
sky units):
# output table in non-verbose mode
[sh] funsky -T snr.ev dd.in MYRA:d MYDEC:d
X Y
------------ ------------
510.00 510.00
512.00 510.50
513.50 513.50
# output table in verbose mode
[sh] funsky -T -v snr.ev dd.in MYRA:d MYDEC:d
# IFILE = /Users/eric/data/snr.ev
# ICOL1 = MYRA
# ICOL2 = MYDEC
# IUNITS1 = d
# IUNITS2 = d
# OCOL1 = X
# OCOL2 = Y
MYRA MYDEC X Y
------------ ------------ ------------ ------------
344.740432 58.606523 510.00 510.00
344.731900 58.607634 512.00 510.50
344.725500 58.614301 513.50 513.50
Finally, the B<-d> (ds9) switch mimicks ds9's use of integer TLMIN
and TLMAX values for all coordinate transformations. FITS conventions
seem to call for use of floating point TLMIN and TLMAX when the data are
floats. This convention is followed by funsky but results in a
small discrepancy with ds9's converted values for floating point
data. We will remedy this conflict in the future, maybe.
=head1 SEE ALSO
See funtools(n) for a list of Funtools help pages
=cut
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